Battery Design Module Updates
For users of the Battery Design Module, COMSOL Multiphysics® version 6.3 introduces new functionality for single-particle electrode modeling, a new interface to model transport in any electrolyte solution, and the ability to specify currents in terms of C rate. Learn more about these updates below.
Features for Single-Particle Electrode Modeling
A Two electrodes model option has been added to the Lumped Battery interface that can be used to define the electrode potential, initial host capacity, and degree of conversion individually for the two electrodes in a battery. The functionality also allows users to define individual electrode properties in order to account for ohmic activation and concentration overpotentials. When the concentration overpotentials are included, the lumped battery Two Electrodes model becomes identical to what in literature is commonly referred to as a single-particle model (SPM).
Additionally, a Thin Porous Electrode feature has been introduced to the Lithium-Ion Battery and Battery with Binary Electrolyte interfaces. It can be used to define electrodes at domain boundaries instead of defining a domain. The feature implements an SPM assuming that the current distribution and electrolyte composition are constant along the electrode thickness — for example, during moderate loads. It is also possible to combine this boundary feature with concentrated solution theory for electrolyte transport in the separator domain, a modeling approach that is referred to as a single-particle model with electrolyte dynamics (SPMe) in scientific literature.
You can view these features in the Single-Particle Modeling of Lithium-Ion Batteries tutorial model.
C-Rate Option for Specifying Total Currents
A setting for specifying the current in terms of a C rate at current collector boundaries is now available. A 1C rate corresponds to the current required to fully charge or discharge a battery in one hour. The C-rate multiple option is available in all electrode features where a total current condition can be specified, for example, in the Lumped Battery interface and, when the SOC and Initial Charge Distribution feature is enabled, in the Lithium-Ion Battery and Battery with Binary Electrolyte interfaces. The following tutorial models demonstrate this new feature:
- lmo_decomposition (new)
- li_battery_multiple_materials_1d
- li_battery_solid_electrolyte
- li_battery_thermal_2d
- li_plating
- lib_single_particle
- lumped_li_battery_capacity_loss
- pouch_cell_utilization
- sei_formation
Concentrated Electrolyte Transport Interface
A Concentrated Electrolyte Transport interface is now available for modeling transport in any electrolyte solution with an arbitrary number of charged and uncharged species. This electrochemistry interface is based on concentrated solution theory, where the transport equations are defined using binary Maxwell–Stefan diffusion coefficients assuming local electroneutrality. In contrast to the Nernst–Planck equations, the concentrated solution theory does not assume the electrolyte species to be diluted in a neutral solvent of constant concentration. Typical electrolytes that can be modeled include ionic liquids, salt melts, and highly concentrated solutions featuring nonnegligible concentration gradients of the charge-carrying species. The new Molten Carbonate Transport tutorial model showcases this functionality.
Logarithmic Formulation for Electrolyte Mass Transport
A logarithmic formulation for the electrolyte salt concentration has been added to the Lithium-Ion Battery and Battery with Binary Electrolyte interfaces. The new formulation eliminates issues related to negative values (due to numerical errors during iteration) of the salt concentration in an electrolyte. The functionality improves convergence during the solution of the model equations for models with high charge and/or discharge rates, which may result in local depletion of electrolyte salt in the electrodes. The logarithmic formulation is especially useful when running parameter estimation or surrogate model training for improving convergence throughout the parameter space. The Surrogate Model Training of a Battery Rate Capability Model and Surrogate Model of a Battery Test Cycle tutorial models show this new update.
Explicit Event List Feature in the Events Interface
An explicit event is often used in the Events interface to momentarily stop the time-dependent solver, redefine the value of one or several state variables at a given explicit time, and then restart the solver. Defining load changes in a battery model using events instead of time-dependent continuous functions can yield considerable performance gains because the continuous transition between the current load steps does not have to be resolved with respect to time. In the Events interface, a new Explicit Event List feature makes it possible to define multiple explicit events using a list of times and corresponding variable values for a common state variable. The input is in the form of a table, which means that the list of events can be loaded from a text file. The 1D Lithium-Ion Battery Drive-Cycle Monitoring tutorial model has been updated to use this new feature.
Result Templates in the Chemical Species Transport Interfaces
Creating useful and visually appealing plots of reacting systems can be time consuming since there are often many reactants and thus many concentration fields to plot. To save time, there are a number of new Result Templates in the Chemical Species Transport interfaces. Among these, plot array templates are now available that include up to four species concentrations simultaneously in the Graphics window. The Result Templates are available for all Chemical Species Transport interfaces, independent of the add-on product, but are especially useful for the multicomponent transport interfaces included in the modules for chemical engineering as well as in the CFD Module, Porous Media Flow Module, Subsurface Flow Module, and Microfluidics Module.
New and Updated Tutorial Models
COMSOL Multiphysics® version 6.3 brings several new and updated tutorial models to the Battery Design Module.
Lithium Plating and Stripping
Copper Current-Collector Dissolution
LMO Decomposition
Surrogate Model of a Battery Test Cycle
Heterogeneous Lithium-Ion Battery
Single-Particle Modeling of Lithium Ion-Batteries
